A. Field of the Invention
The present invention relates to lighting fixtures that produce high intensity, controlled, and concentrated light beams for use at relatively distant targets. One primary example is illumination of a sports field.
B. Problems in the Art
The most conventional form of sports lighting fixture 2 is a several feet in diameter bowl-shaped aluminum reflector with a transparent glass lens 3 suspended from a cross arm 7 fixed to a pole 6 by an adjustable knuckle 4 (see FIG. 1B).
This general configuration of sports lighting fixtures 2 has remained relatively constant over many years because it is a relatively economical and durable design. It represents a reasonable compromise between the desire to economically control high intensity light to a distant target while at the same time minimizing wind load, which is a particularly significant issue when fixtures are elevated out-of-doors to sometimes well over 100 feet in the air. A much larger reflector could control light better. However, the wind load would be impractical. A significant amount of the cost of sports lighting systems involves how the lights are elevated. The more wind load, the more robust and thus more expensive, the poles must be. Also, conventional aluminum bowl-shaped reflectors are formed by a spinning process. Different light beam shapes are needed for different fixtures 2 on poles 6 for different lighting applications. The spinning process for creating aluminum bowl-shaped reflectors is relatively efficient and economical, even for a variety of reflector shapes and light controlling effects. The resistance of aluminum to corrosion is highly beneficial, particularly for outdoors lighting.
In recent times, sports lighting has also had to deal with the issue of glare and spill light. For example, if light travels outside the area of the sports field, it can spill onto residential houses near the sports field.